Tone-amplifying apparatus for musical instruments



Oct. 7 1924. 1,510,476

F. c. HAMMOND TONE AMPLIFYING APPARATUS FOR MUSICAL INSTRUMENTS OriginalFiled July 8, 1922 0 74 f 5 z w r1 11 ATTERY- 1 ,2

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' UNITEDFSTA FRED C. HAIIOND, 01' CHABLESTOWN, NEW EAIQSE IBE,ASSIGNOROI ONE-HALF r wanna w. snacx, or sramermnn, vmmonr.

roflmmrmo arr'uwrus roa MUSICAL msraunnn'ra Application filed July3,1922, Serial no. traces. lenewed rebmar a7, 1924.

To all whom it may concern.- Be it known that I, Fnnn C. HAMMOND, a

.citizen of the United States, residing at Gharlestown, in the count ofSullivan-and State of New, Hampshire, ave inventednew and-usefulImprovements in Tone-Amplify ing Apparatus for Musical- Instruments, of

which the following is a specification.

: vice.

,trating a difierent arrangement.

Thisinventiomrelates to means'for amplifying the toneg of a musicalinstrument having a resonant element, such as the body of a violin,violincello, viola, banjo, guitar, or mandolin, or the sound board of aharp or iano, the amplification being capable of i-ng instantly changedby a leader or director, while the instrument is being played byaperformer, to vary the volume of tone coming from the instrument.

An object of'the invention is to provide a suitable device associatedwith the resonant element of the instrument, and connected with suitableelectrical amplifying means, which is in turn connected with a receiveror loud speaker, whereby a. director may vary the volume of tone of aninstrument, or any number of instruments.

A further object of the invention isto provide a musical instrumentwhich includes a sound post, such as'that of a violin, etc.,'and .amicrophone associated with the sound post, and electrically connectedwith one or more stages of amplification, and in turnconnected with areceiver or loud speaker.

Other objects will appear as the description proceeds. Y

' Of the accompanyingdrawings forming a part of this specification,

Figure 1 is a plan view of a violin showing the position of themicrophone-carrying sound Post. 1

Figure '2 is a longitudinal section of a ,violin, showing themicrophone-carrying sound post in position between the front and back ofthe violin. I

Figure 3' is a diagrammatic view, illus trating asuitable arrangement ofthe wiring of the circuits for the tone-amplifying de- Figure 4 is adiagrammatic view illus-' Figure 5 is. a diagrammatic view, illustratinganotherarrangement.

Like characters .of reference are used throughout the followingspecification, to designate like parts.

' the volume of music coming adapting my invention to a violin, orsimilar instrument, which includes a 'resonant body 1, and a sound post2, I preferably provide the sound post with an enlarged connection'onthe microphone. This circuit is called the primary circuit, and collectsthe tone vibrations when the instrument is played.

" I The secondary circuit commences with one side of the secondary ofthecoil 8, and connectswith the grid 9 of an amplifier 01 audion bulb 1O.The plate 11 of the bulb 10 connects with the positive side ofthe Bbattery, which is preferably approximately twenty-two volts. Thenegative side of the B battery connects to one post. of a loud speakingreceiver 12, and from thence to the post 13, and back to the oppositeend of the secondary of the coil 8.

A third circuit connects the negative pole.

of a six-volt A or lighting battery with the pole 13, and from thence toone side of the filament 14. The other side of the filament connectswith the arm 15 of the rheostat 16,

and from thence back to the A battery. From the foregoing description,it will be seen that the sound waves from the instrument will be pickedup by thernicrophone, and will be induced from the primary of the coilto the secondary of the coil. The amplifier bulb .10 Will amplify thewaves many times, until they are collected by the receiver 12, whichalso amplifies'the volume. It will be' apparent that as many steps ofamplification may be used as desired, so that an orchestra director mayreadily change from the instruments equipped with this apparatus, tosuitthe requirements of the musical number being played. i

The principle involved in this device is much similar to that of thewireless telethe positive side of phone, wherein the loudness of thesignals I such installation is complete, an orchestra director will havethe highest degree of control over his orchestra, and may modify thetone of each instrument independently of the player.

In applying my invention to a musical instrument which does not includea sound post, and includes a resonant element, such as the soundboard ofa piano, the microphone may be secured in any suitableway to theresonant element, care being taken to prevent dampening of thevibrations. It will be understood that many minor changes in details andarrangement may be resorted to without departing from the spirit'of theinvention. For example, the arrangement shown diagrammatically by Figure4 may be employed. This arrangement dispenses with the dry cells 7, andswitches off the current automatically when the filament is cut off.

The arrangement shown diagrammatically by Figure 5, materially reducesthe noises from a violin or similar instrument, caused by movements ofthe players hand, and the scratching of the bow. This arrangementincludes a three point switch 20, adapted to cut out amplification toany extent desired. In experimenting with apparatus, including thearrangement shown by Figure 5, l have attached the first tube plate tothe third, with great improvement in the quality and volume of tone.

The invention may be adapted to wind rai er/e instrument, the shape andmaterial of the instrument giving the tone quality peculiar to theinstrument, whether it be of brass or wood. The vibrating air leaves thebell in cone form, and is applied directly to a microphone supported byany suitable means in the path of the vibrating air, the vibrationspassing through the amplifying'tub-es to any extent desired. Theamplified tones blend with those of the instrument.

I claim:

1. A device of the character described comprising a sound post for aninstrument of the violin type, provided with an enlarged hollowed outcentral portion adapted to receive and house a microphone, incombination with means for amplifying the microphone current.

2. A sound post for an instrument of the violin type, provided with anenlarged hollowed out central portion, a microphone adapted to seattherein, and an electrical amplifying circuit for said microphone.

3. A sound post for an instrument of the violin type, provided with anenlarged hollowed out central portion, a miorophone adapted to seattherein, and an electrical amplifying circuit including a loudspeakingunit for said microphone.

In testimony whereof Ihave afiixed my signature.

FRED C. HAWOND.

